Amethyst is the widely known and very popular purple form of macrocrystalline Quartz, and is in fact one of the most valuable forms of the common mineral. Amethyst is famous for its purple color, which is caused by iron impurities within the structure of the Quartz crystal. Beyond the traditional big four ‘precious stones’, which are Diamond, Ruby, Sapphire, and Emerald, Amethyst is probably the most recognizable and well known type of gemstone to the general public. Amethyst is also the birthstone for February.
Etymology & Sources
The name ‘Amethyst’ is derived from the Greek word ‘Amethystos’ which translates to ‘not drunken’, and ancient Greeks believed that Amethysts had the ability to protect against or prevent inebriation (in our experience, it doesn’t work). Because of this, it is not uncommon to see historical wine vessels and goblets encrusted with the purple gemstone. Purple was also historically considered the color of royalty and as such the Amethyst was particularly popular among the nobility. Historically speaking, Amethysts were considered very rare until large supplies of it were found in deposits in Brazil around the turn of the 19th century. Nowadays, Amethysts are much more common than they were, and deposits exist in Brazil, Bolivia, Canada, Russia, and many other places.
Amethyst is purple, and can range from a light, lilac color to a deep and intense purple. Amethyst can range from transparent to translucent, and has a vitreous luster. The most valuable forms of the gemstone are generally the darker deep purple variety, and higher clarity is typically heavily favored. Since Amethyst is a form of Quartz, it has decent hardness suitable for many different decorative applications.
Amethyst has a Moh scale hardness of around 7, similar to other Quartz, and has a specific gravity of about 2.65 and a refractive index value of roughly 1.55.
Higher quality Amethyst is usually faceted into traditional gemstone shapes, but sometimes lower quality, lighter or more translucent amethyst is cut en cabochon or into beads – these are particularly popular with jewelry making enthusiasts. Due to the availability of large Amethyst crystals, carvings and other ornaments can also be carved. Amethyst can also be found sold in geode form, either for decorative purposes or, for those that believe in crystal healing, for health reasons.
- Amethyst Quartz – Usually a mixture of Amethyst and Clear Quartz, it is typically a mixture of a white milky color and purple. It is rarely faceted and most often formed into beads or cabochons.
- Green Amethyst – Light green form of Quartz, where the colors are artificially created by subjecting Amethyst to heat treatment. Can also be known as Prasiolite.
- Ametrine – Natural mixture of Amethyst and Citrine that often has clear and abrupt split between the purple Amethyst part and the yellow Citrine part. Only comes naturally from one source in Bolivia, but can also be synthetically created.
Amethyst is occasionally heat treated to improve the intensity of the purple color.Heat treatment can also be used to turn Amethyst into Citrine, or the artificial green Quartz variety Prasiolite (mentioned above). Amethyst can also be created synthetically.